Delivering variable positive airway pressure depending on awake state and sleep disordered breathing

ABSTRACT

Positive airway pressure (“PAP”) systems and methods are provided which supply a patient with a range of pressures for treatment when the patient is determined to be asleep, and an awake pressure for use when the patient is determined to be awake, the awake pressure configured for the comfort of the patient. The awake pressure is configured to be lower than the lower bound of the pressure range and can be a therapeutic or sub-therapeutic pressure. The PAP systems and methods disclosed herein advantageously allow for the pressure range to be tailored for effective treatment of sleep disordered breathing while allowing the awake pressure to be set for the comfort of the patient. This can advantageously increase both the efficacy of the treatment of SDB and patient compliance with the treatment.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/301,332, filed Sep. 30, 2016, which is a U.S. National Phase ofInternational Patent Application No. PCT/M2015/052255, filed Mar. 27,2015, which claims priority to U.S. Provisional Application No.61/974,310, filed Apr. 2, 2014, which is hereby incorporated byreference herein in its entirety.

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND Field

The present disclosure relates to systems for treating obstructive sleepapnea by providing positive airway pressure to a patient, in particular,to methods for the device to adjust the treatment pressure in responseto the patient's awake state and sleep disordered breathing.

Description of Related Art

One major treatment approach for obstructive sleep apnea includesproviding breathing gases to the patient throughout the period thepatient is asleep. These treatments may collectively be known aspositive airway pressure therapy (PAP). Variations on this therapyinclude having different inspiration and expiration pressures, commonlyknown as bi-level or bi-PAP, or having continuously adjusting therapywhich responds to breathing events.

SUMMARY

The systems, methods and devices described herein have innovativeaspects, no single one of which is indispensable or solely responsiblefor their desirable attributes. Without limiting the scope of theclaims, some of the advantageous features will now be summarized.

The present disclosure describes a positive airway pressure system thatdelivers gas to a patient when asleep, the gas having a pressure withina range of asleep pressures, and a different awake pressure when thepatient is awake, the awake pressure being lower than the minimumpressure in the range of asleep pressures. This can advantageouslyimprove the comfort of the device for a patient, which can increasecompliance with the positive airway pressure therapy. Increasedcompliance generally improves the results of the therapy for thepatient.

In a first aspect, a positive airway pressure system is provided whichincludes a flow generator configured to provide gas at a pressure to apatient. The positive airway pressure system also includes a userinterface configured to provide to the patient the gas at the pressureand a conduit that provides a path for the gas from the flow generatorto the user interface. The positive airway pressure system also includesa sensor configured to measure breathing of the patient. The positiveairway pressure system also includes a control system configured todetect sleep disordered breathing based at least in part on analysis ofdata acquired by the sensor; determine a sleep state of the patientbased at least in part on analysis of data acquired by the sensor;control the flow generator to provide a pressure between a low pressureand a high pressure when the sleep state is determined to be asleep, thepressure provided based at least in part on whether sleep disorderedbreathing is detected; and control the flow generator to provide anawake pressure different from the low pressure if the sleep state isdetermined to be awake, the awake pressure is selected by a user.

In some embodiments of the first aspect, the awake pressure is atherapeutic pressure. In some embodiments of the first aspect, the awakepressure is lower than the low pressure.

In some embodiments of the first aspect, the controller is furtherconfigured to control the flow generator to provide a pressure whichincreases over time at a first pressure ramp rate when the pressurebeing provided by the flow generator is the awake pressure and the sleepstate is determined to be asleep or sleep disordered breathing isdetected. In a further embodiment, the first pressure ramp rate isadjustable by a user. In some embodiments of the first aspect, thecontroller is further configured to control the flow generator toprovide a pressure which decreases over time at a second pressure ramprate when the pressure being provided by the flow generator is betweenthe low pressure and the high pressure and the sleep state is determinedto be awake. In a further embodiment, the second pressure ramp rate isadjustable by a user.

In some embodiments of the first aspect, the low pressure and the highpressure are adjustable by a user. In some embodiments of the firstaspect, the sensor is one of a flow sensor, a pressure sensor, a soundsensor, a motion sensor, or a plethysmograph sensor.

In a second aspect, a method is provided for supplying positive airwaypressure therapy to a patient. The method includes receiving input froma user to set an awake pressure, detecting a presence of sleepdisordered breathing; determining a sleep state of the patient; if thesleep state is determined to be asleep, delivering gas having an asleeppressure that is adjusted between a low asleep pressure and a highasleep pressure, the asleep pressure depending at least in part on thepresence of sleep disordered breathing; and if the sleep state isdetermined to be awake, delivering gas having the awake pressure, theawake pressure different from the low asleep pressure.

In some embodiments of the second aspect, the awake pressure is atherapeutic pressure. In some embodiments of the second aspect, theawake pressure is lower than the low asleep pressure.

In some embodiments of the second aspect, the method further includesincreasing a pressure of the gas delivered at a first ramp rate when thepressure being delivered has the awake pressure and the sleep state isdetermined to be asleep or sleep disordered breathing is detected. In afurther aspect, the method includes receiving input from a user to setthe first ramp rate.

In some embodiments of the second aspect, the method includes decreasinga pressure of the gas delivered at a second ramp rate when the pressurebeing delivered is between the low asleep pressure and the high asleeppressure and the sleep state is determined to be awake. In a furtheraspect, the method includes receiving input from a user to set thesecond ramp rate.

In some embodiments of the second aspect, the method includes receivinginput from a user to set the low asleep pressure and the high asleeppressure. In some embodiments of the second aspect, detecting a presenceof sleep disordered breathing comprises analyzing values from a sensor,the sensor comprising at least one of a flow sensor, a pressure sensor,a sound sensor, a motion sensor, or a plethysmograph.

In a third aspect, a user interface is provided that is communicablycoupled to a control system of a positive airway pressure apparatus. Theuser interface includes an awake pressure node configured to receiveawake pressure data indicative of an awake pressure. The user interfaceincludes a low pressure node configured to receive lower bound dataindicative of a lower bound of a pressure range. The user interfaceincludes a high pressure node configured to receive upper bound dataindicative of an upper bound of the pressure range. The user interfacecommunicates the awake pressure, the lower bound of the pressure range,and the upper bound of the pressure range to the control system, and thecontrol system controls the positive airway pressure apparatus to supplya breathing gas having the awake pressure if a sleep state is determinedto be awake, the awake pressure is different from the lower bound of thepressure range.

In some embodiments of the third aspect, the awake pressure is less thanthe lower bound of the pressure range. In some embodiments of the thirdaspect, the user interface further includes a ramp rate node configuredto receive ramp rate data indicative of a pressure ramp rate. In afurther embodiment of the third aspect, the control system transitionsfrom providing the awake pressure to a pressure within the pressurerange at the pressure ramp rate.

BRIEF DESCRIPTION OF THE DRAWINGS

Throughout the drawings, reference numbers can be reused to indicategeneral correspondence between reference elements. The drawings areprovided to illustrate example embodiments described herein and are notintended to limit the scope of the disclosure.

FIG. 1 illustrates a PAP system configured to provide PAP therapy to apatient, wherein the PAP system includes a flow generator, a controller,a patient interface, and a conduit connecting the patient interface andthe flow generator.

FIG. 2 illustrates a block diagram of an example PAP system configuredto provide an awake pressure when a patient is awake and a range ofpressures when the patient is asleep, the minimum pressure in the rangebeing different than the awake pressure.

FIG. 3 illustrates a plot of pressure for delivery to a patient as afunction of time, the plot demonstrating different events and responsesto the events.

FIG. 4 illustrates a flow chart of an example method of delivering anawake pressure to a patient and a range of pressures when the patient isasleep, the minimum pressure in the range being different from the awakepressure.

DETAILED DESCRIPTION

Certain embodiments and examples of systems and methods for providingpositive airway pressure are described herein. The systems and methodsgenerally include providing a range of pressures to treat sleepdisordered breathing when a patient is determined to be asleep and anawake pressure when the patient is determined to be awake. The range ofpressures and the awake pressure can include therapeutic and/orsub-therapeutic pressures. Those of skill in the art will appreciatethat the disclosure extends beyond the specifically disclosedembodiments and/or uses and obvious modifications and equivalentsthereof. Thus, it is intended that the scope of the disclosure not belimited by any particular embodiments described herein.

As used herein, the term sleep disordered breathing is a broad term andis intended to have its plain and ordinary meaning to those of ordinaryskill in the art and includes at least any of a group of disorderscharacterized by abnormalities of respiratory pattern (e.g., pauses inbreathing). Sleep disordered breathing includes, for example and withoutlimitation, obstructive sleep apnea, upper-airway resistance syndrome,Cheyne-Stokes respiration, and the like.

As used herein, the term therapeutic pressure is a broad term and isintended to have its plain and ordinary meaning to those of ordinaryskill in the art and includes at least a pressure configured to beeffective in treating sleep disordered breathing. A sub-therapeuticpressure, by comparison, is a pressure that is below the pressure whichis effective for treating sleep disordered breathing. Whether a pressureis therapeutic can be patient- and/or time-dependent. For example, apressure of 10 cmH2O can be a therapeutic pressure at one instance intime for a particular patient because it would reduce or eliminate inthat patient sleep disordered breathing at that time and, by extension,any pressure below 10 cmH2O would be a sub-therapeutic pressure for thatpatient at that time.

Positive airway pressure (“PAP”) systems can be configured to provide acontinuously adjustable pressure configured to treat sleep disorderedbreathing (“SDB”). A pressure algorithm can be used which analyzes apatient's breathing to determine a pressure to deliver to the patient.The pressures to be delivered to the patient, or the pressuresdetermined by the pressure algorithm for delivery to the patient, can beconstrained to be within a pressure range. The pressures within thepressure range, however, can be uncomfortable for a patient who is awakeor who awakens during treatment. In some PAP systems, then, the minimumpressure of the pressure range can be delivered when the patient isdetermined to be awake to reduce discomfort to the patient.

There are competing interests in this situation which may reduce orprevent effective treatment of SDB. First, it is desirable to set thepressure range for effective treatment of SDB. It is desirable, forexample, to restrict the amount of pressure adjustability (e.g., byrestricting the size of the pressure range). Restricting the amount ofpressure variability may reduce the likelihood of SDB events due atleast in part to inappropriately applied sub-therapeutic pressures.Restricting the amount of pressure variability may also reduce orprevent transient large swings in pressure and reduce or preventinappropriate or undesirable pressure increases.

Second, it is desirable to set the lower bound of the pressure range forthe comfort of the patient when awake. Generally, the lower the pressurethe more comfortable the treatment is for a patient while they areawake. Accordingly, it may be desirable to set the lower bound of thetreatment range to a relatively low pressure setting or the lowestavailable pressure setting (e.g., about 4 cmH2O). However, a comfortablepressure may not effectively treat SDB. Setting the lower bound of thepressure range to be comfortable for the patient, then, makes it so thatthe pressure algorithm is less effective in treating SDB. Thus, if thelower bound of the pressure range is configured to be comfortable forthe patient while awake, there may be confusion or a conflict on thepart of the clinician, physician, or user on how to set this pressure.For example, there may be a conflict or confusion regarding whether thelower bound should be set for comfort while the patient is awake orwhether it should be set higher to provide effective therapy whileasleep.

Accordingly, PAP systems and methods are provided which utilize anadditional parameter, the awake pressure, to address these issues. ThePAP systems and methods disclosed herein provide for a pressuretreatment range for use when the patient is determined to be asleep, andan awake pressure for use when the patient is determined to be awake,the awake pressure configured for the comfort of the patient. The awakepressure is configured to be lower than or equal to the lower bound ofthe pressure range and can be a therapeutic or sub-therapeutic pressure.The awake pressure can differ depending at least in part on thepreference of the patient. The PAP systems and methods disclosed hereinadvantageously allow for a physician, clinician, or user to tailor thepressure range for effective treatment of SDB while allowing the awakepressure to be set for the comfort of the patient. This canadvantageously increase both the efficacy of the treatment of SDB andpatient compliance with the treatment.

Positive Airway Pressure Apparatus

FIG. 1 is a diagram illustrating an example PAP system configured tosupply breathing gases with pressures determined as described herein.The system includes an apparatus 200 for delivering a supply ofbreathing gases, a supply conduit 202, and a patient interface 204. Thepressure of the breathing gases provided by the apparatus 200 can varybased on conditions detected by the system. The system can vary theprovided pressure in response to sleep disordered breathing, where thevariation in the pressure can be constrained to be within lower andupper bounds. The system can provide an awake pressure when a patient isdetermined to be awake, the awake pressure lower than or equal to thelower bound of the pressure range.

The system includes the supply conduit 202 which extends from an outletof the gases supply apparatus to the patient interface 204. The supplyconduit 202 is configured to deliver the pressurized breathing gases tothe patient interface 204. The patient interface 204 includes a biasflow vent 206 for allowing a controlled leak from the patient interface204. The controlled leak allows the inside of the patient interface 204to be continuously flushed by fresh gases supplied by the supplyapparatus 200. The patient interface 204 may comprise any of the manytypes of typical patient interface for PAP delivery, for example, nasalmask, full face mask, oral mask, oral interface, nasal pillows, nasalseal or nasal cannula. The bias flow vent 206 may be located directly onthe patient interface 204, or adjacent the patient interface 204 on aconnector between the patient interface 204 and the supply conduit 202or through the wall of the supply tube 202, close to the patientinterface 204. A wide variety of patient interfaces and conduits areknown in the art.

The supply apparatus 200 includes a flow generator 209. The flowgenerator 209 can comprise a fan 210 driven by an electric motor 212.Air is drawn through an inlet 214 in the housing of the apparatus 200 bythe fan 210. Pressurized air leaves the fan 210 for delivery to thepatient through supply conduit 202 and user interface 204. In someembodiments, controllable flow generators may draw on a source of highpressure gas, and regulate a flow of gas from the high pressure source.

The apparatus 200 may include a humidifier 216, for example in the formof a pass-over humidifier where air passing through the humidifierchamber picks up a quantity of water vapor from a reservoir of water218. The water reservoir 218 may be heated by a heater 220. Thehumidifier 216 may be integrated with the housing of the flow generator209 or a separate, optional, component.

The heater 220 and motor 212 are supplied with power from a power supply222. The amount of power to the motor 212 and the amount of power to theheater 220 can be controlled by the control system 224. The controlsystem 224 is also supplied with power from the power supply 222.

The control system 224 can be configured to receive input from a userinterface 226. For example, the control system 224 can receive userinput to set the pressure range and/or the awake pressure, as well asother parameters associated with the operation of the apparatus 200.

The control system 224 may also include a communication port 228 forconnecting with an external data source or other external system. Theexternal data source or system may, for example, include a communicationinterface such as a modem or router, or may be an interface to anexternal memory such as a smart card, disk drive, flash memory or thelike. For generic use, the communication port 228 may be a datacommunication port according to any of the many available standards, forexample, a universal serial bus (USB) port. A USB (or similar) interfacecan be used for connecting a wide range of peripheral devices.

As described in greater detail with reference to FIG. 2, the controlsystem 224 can include a controller such as a computer processor (e.g.,an embedded microcomputer with stored control programs). In certainembodiments, the control system 224 may comprise a fixed electroniccircuit implementing programmed functionality, or a programmed logiccircuit (such as an FPGA) implementing the programmed functionality. Inaddition, the control system 224 can include a non-transitory storagemedium such as computer memory configured to store executableinstructions that, when executed, cause the controller to performprogrammed functions. Examples of programmed functions includedetermination of a pressure setpoint, determination of a patient sleepstate, detection of sleep disordered breathing, or other functions tocontrol the apparatus 200.

The apparatus 200 can include one or more sensors. The one or moresensors can include a flow sensor 230 and may also include a pressuresensor 232 downstream of the fan 210. The flow sensor 230 may beupstream or downstream of the fan 210. The one or more sensors caninclude, for example and without limitation, the flow sensor 230, thepressure sensor 232, a sound sensor, a motion sensor, a plethysmograph,and the like.

The control system 224 can be configured to receive data acquired by theone or more sensors. Based at least in part on the acquired data, thecontrol system 224 can be configured to detect a sleep state of thepatient. Similarly, based at least in part on the acquired data, thecontrol system 224 can be configured to detect sleep disorderedbreathing. When the patient is asleep, the control system 224 canutilize a pressure algorithm to determine an appropriate or targetedpressure of breathing gases to supply to the patient wherein thepressure determined by the pressure algorithm is based at least in parton any detected sleep disordered breathing events. When the patient isdetermined to be awake, the control system 224 can be configured tocontrol the apparatus 200 to deliver the awake pressure.

The pressure algorithm can be configured to determine a target pressurefor supplied breathing gases, the target pressure based at least in parton current and/or historical supplied pressure and the presence of sleepdisordered breathing. In some embodiments, the pressure algorithm canincrease the pressure of the supplied breathing gases when sleepdisordered breathing is detected. In some instances, the pressure cancontinue to increase (e.g., in discrete or continuous pressureincrements) while the sleep disordered breathing continues. In someinstances, the pressure can decrease (e.g., in discrete or continuouspressure decrements) while there is no sleep disordered breathing.

The pressure algorithm can be limited to a range of pressures. Forexample, the control system 224 can provide a minimum pressure and amaximum pressure to the pressure algorithm such that the pressurealgorithm is restricted to output pressures within the range inclusiveof the minimum and maximum pressures. The range of pressures can includetherapeutic pressures, sub-therapeutic pressures, or both therapeuticand sub-therapeutic pressures. The range of pressures can be configuredsuch that the minimum and maximum pressures bracket a determined,targeted, or optimal pressure. For example, where it is determined thata pressure of approximately 12 cmH2O is an effective therapeuticpressure for a patient, the lower bound of the pressure range can be setto 9 cmH2O and the upper bound of the pressure range can be set to 15cmH2O. By setting this range, the control system 224 allows the pressurealgorithm to respond to changes in patient state that merit or requiredifferent pressures but limits or prevents the apparatus 200 fromproviding under- and/or over-treatment. For example, where the pressurealgorithm determines that an appropriate or optimal pressure for apatient is approximately 12 cmH2O, this value may change depending onwhether the patient is sleeping on their back or on their side. Otherfactors may affect an appropriate or therapeutic pressure including, forexample and without limitation, alcohol consumption, sleep states, apatient's physical characteristics, and the like.

When the patient is awake, the control system 224 can be configured tocontrol the apparatus 200 to supply breathing gases at an awake pressurethat is lower than or equal to the lower bound of the pressure rangeutilized by the pressure algorithm. The awake pressure can be configuredto be more comfortable for the patient relative to the pressures in thepressure range. Increasing the comfort of the patient can increasecompliance with the positive airway pressure therapy, thereby increasingthe efficacy of the treatment. The awake pressure can be a therapeuticor a sub-therapeutic pressure. The awake pressure can be adjusted and/orselected by a patient, physician, user, clinician, or the like.

The control system 224 can be configured to control the apparatus 200 totransition between supplying breathing gases at the awake pressure andsupplying breathing gases within the pressure range. When a change in apatient's sleep state is determined by the control system 224, thecontrol system 224 can employ a transition function to ramp the pressureup or down between the awake pressure and the pressure range, dependingon whether the patient is waking up or falling asleep.

Positive Airway Pressure Control System

FIG. 2 illustrates a block diagram of an example PAP control system 224configured to control a PAP apparatus (e.g., the apparatus 200 describedwith reference to FIG. 1) to provide an awake pressure when a patient isawake and a range of pressures when the patient is asleep, the lowerbound of the pressure range being greater than the awake pressure. Thecontrol system 224 can be configured to receive input from sensors 302and/or user interface 204, to determine a sleep state of a patient, todetect sleep disordered breathing, to determine a targeted pressurebased at least in part on input received from the sensors and/or user,and/or to control a flow generator to supply breathing gases having thetargeted pressure. The sensors 302 can include one or more of a flowsensor, a pressure sensor, a sound sensor, a motion sensor, and/or aplethysmograph. The interface 226 can be any suitable system whichallows a user to provide data to the control system, such as through atouch screen interface, a keyboard, a display, buttons, switches, or anycombination of these or similar elements. The control system 224 can beimplemented using hardware, software, firmware, or any combination ofthese.

The control system 224 includes a controller 305 comprising one or morecomputer processors. The control system 224 includes data storage 310comprising non-transitory computer memory. The control system 200includes modules 320, 325, 330, 335 configured to analyze sensor dataand user input to determine a targeted pressure to supply to a patient.In some embodiments, one or more of the modules 320, 325, 330, or 335utilizes the controller 305 and/or data storage 310 to accomplish itsfunctionality. The controller 305, data storage 310, and modules 320,325, 330, and 335 can be configured to communicate with one another overcommunications bus 315. The communications bus 315 can be any standardcommunications bus. The communications bus 315 can at least partiallyinclude a networked connection, using either wireless or wiredconnections. The communication bus 315 can include communication betweenprocesses or functions being executed by one or more of the modules 320,325, 330, or 335 and/or the controller 305.

The control system 224 includes the sleep determination module 320configured to analyze data acquired by one or more of the sensors 302 todetermine a sleep state of a patient. In some embodiments, the sleepdetermination module 320 assigns the sleep state of the patient to beeither asleep or awake. Generally, the sleep determination module 320can analyze sensor data to identify breathing patterns indicative ofsleep. Any suitable methods of making a determination that the user isasleep or is awake can be used. Some suitable methods are described inother patent publications, for example, U.S. Pat. No. 6,988,994 and U.S.Pat. Pub. No. 2008/0092894, each of which is hereby incorporated byreference in its entirety.

The control system 224 includes the SDB detection module 325 configuredto analyze data acquired by one or more of the sensors 302 to detect SDBevents such as apneas, hypopneas, flow limitations, or the like.Generally, the SDB detection module 325 can analyze sensor data toidentify breathing patterns indicative of SDB events. Examples oftechniques used to detect SDB events are disclosed in U.S. Pat. No.7,882,834 to Gardon et al., entitled “Autotitrating Method andApparatus,” issued Feb. 8, 2011, the entire contents of which is herebyincorporated by reference in its entirety.

The control system 224 includes the pressure control module 330configured to analyze the sleep state of the patient and any SDB eventsto determine a pressure of a breathing gas to supply to the patient. Forexample, if the patient is awake, the pressure control module 330 canindicate to the control system 224 that the awake pressure should besupplied to the patient. If, on the other hand, the patient is asleep,the pressure control module 330 can utilize a control algorithm todetermine the pressure to supply to the patient, the pressure beingwithin the pressure range (e.g., not to exceed the upper bound of thepressure range or the maximum pressure and not to be below the lowerbound of the pressure range or the minimum pressure). The pressurecontrol module 330 can take into account the presence of one or more SDBevents and adjust the targeted pressure output in response. Variousmethods of control or control algorithms are possible, including themethods described in PCT Publication Number WO 2012/020314, filed Aug.12, 2011 and entitled “APPARATUS AND METHOD FOR PROVIDING GASES TO AUSER,” which is incorporated by reference herein in its entirety. Otherexamples of control methods include, for example, multi-night,auto-cpap, bi-level, auto bi-level, and the like.

The control system 224 includes the transition module 335 configured tomonitor transitions between the awake and asleep sleep states. Thetransition module 335 can work in conjunction with the pressure controlmodule 330 to transition between the awake and asleep control modes. Forexample, when transitioning from an awake state to a sleep state, thetransition module 335 can ramp up the pressure from the awake pressureto the lower bound of the pressure range. Once the pressure reaches thepressure range, the pressure control module 330 can take over control ofdetermining the pressure to supply to the patient. As another example,the transition from the sleep state to the awake state can similarly behandled by the transition module 335 which can ramp down the pressurefrom the pressure range to the awake pressure. The ramp rates forincreasing the pressure and decreasing the pressure can be the same ordifferent from one another. The ramp rates may also be selected oradjusted by a user of the system, such as a clinician, a patient, or aphysician. In some embodiments, the transition module 335 is configuredto ignore SDB events during the transition from the awake state to thesleep state. In some embodiments, if the patient awakes during thetransition to the pressure range from the pressure range, the transitionmodule 335 can ramp the pressure down from the pressure at the time thetransition occurred to the awake pressure.

FIG. 3 illustrates a plot 350 of a pressure of breathing gases suppliedto a patient as a function of time, the plot demonstrating differentevents and responses to the events. The line 355 represents the pressuresupplied to a patient over time. Initially, the pressure supplied to thepatient is the awake pressure, or Pawake. The awake pressure can have arelatively low value, such as greater than or equal to about 4 cmH2O orless than about 4 cmH2O.

While the patient is awake, the pressure supplied remains the awakepressure. Upon the occurrence of an exit trigger, the pressure ramps upto the pressure range, or a pressure between Pmin and Pmax, inclusive.The exit trigger can be, for example and without limitation, two apneaevents (e.g., central or obstructive) within a moving window of 30consecutive breaths, two hypopnea events (e.g. central or obstructive)within a moving window of 30 consecutive breaths, or an event with asequence of three flow-limited breaths in a row. It is to be understoodthat the exit trigger can comprise more than just a transition from anawake sleep state to an asleep sleep state, but can also include otherindications that the patient is asleep, such as apnea events, hypopneaevents, and so forth.

Upon the occurrence of an exit trigger, the pressure supplied increasesfrom the awake pressure to at least the lower bound of the pressurerange. The rate of change of pressure can be configured to reduce orminimize discomfort to the patient. The rate of change can be configuredor adjusted by a user, such as a clinician, patient, or physician. Anexample rate of change from the awake pressure to the pressure range isabout +0.1 cmH2O/s. Other values can also be used, such as at leastabout +0.02 cmH2O/s and/or less than or equal to about +2 cmH2O/s, atleast about +0.05 cmH2O/s and/or less than or equal to about +1 cmH2O/s,or at least about +0.1 cmH2O/s and/or less than or equal to about +0.5cmH2O/s.

During the transition from the awake pressure to the pressure range,certain events can be ignored. For example, SDB events can be ignoredduring the transition as the events will be treated using the pressureswithin the pressure range. Increasing the pressure at a higher rate thanthe designated ramp rate may cause discomfort to the patient. In someembodiments, the ramp rate can change in response to one or more SDBevents.

During the transition from the awake pressure to the pressure range, ifthe sleep state of the patient is determined to be awake. At this point,the supplied pressure can be reduced from its current value to the awakepressure. The rate of change to the awake pressure can have the samemagnitude as the rate of change of increase from the awake pressure orit can be different. An example rate of change to the awake pressure isabout −0.1 cmH2O/s. Other values can also be used, such as where themagnitude of the change is at least about 0.02 cmH2O/s and/or less thanor equal to about 2 cmH2O/s, at least about 0.05 cmH2O/s and/or lessthan or equal to about 1 cmH2O/s, or at least about 0.1 cmH2O/s and/orless than or equal to about 0.5 cmH2O/s.

Once the pressure reaches the lower bound of the pressure range (e.g,Pmin), the pressure algorithm can be used to control the pressure, asdescribed in greater detail herein. For example, the supplied pressurecan be increased in response to an SDB event. Similarly, the pressurecan decrease where the patient is breathing normally. In both instances,the range of pressures provided through the pressure algorithm iscapped, having a lower bound at Pmin and an upper bound at Pmax. As anexample, the pressure range can extend from about 4 cmH2O to about 20cmH2O, where Pmin is greater than or equal to 4 cmH2O, Pmax is less thanor equal to 20 cmH2O, Pmin is less than Pmax, and Pmin is greater thanPawake.

If the patient awakes while the pressure is within the pressure range,the pressure supplied can decrease at the designated rate of change tothe awake pressure.

Method of Delivering Positive Airway Pressure

FIG. 4 illustrates a flow chart of an example method 400 of deliveringan awake pressure to a patient and a range of pressures when the patientis asleep, the minimum pressure in the range being different from theawake pressure. For ease of description, the steps of the method 400will be described as being performed by the control system 224. However,one or more steps of the method can be performed by one or morecomponents of the apparatus 200 and/or the modules 320, 325, 330, 335.In addition, a single step or a combination of steps can be accomplishedthrough the combined efforts and functionality of the systems andmodules described herein.

In block 405, the control system 224 detects a sleep state of thepatient. By monitoring one or more sensors, the control system 224 candetect the sleep state and make a determination of whether the patientis asleep or awake. In some embodiments, the sleep state is detectedthrough monitoring of breathing patterns. Any suitable method ofdetermining the sleep state of the patient can be used. Some suitablemethods are described in other patent publications, for example, U.S.Pat. No. 6,988,994 and U.S. Pat. Pub. No. 2008/0092894, each of which ishereby incorporated by reference in its entirety.

In block 410, the control system 224 proceeds along different controlloops depending on whether the patient is awake. If the patient isasleep, the method 400 continues to block 415 where the control systemdetects sleep disordered breathing. The control system 224 can analyzesensor data to detect SDB events. Examples of techniques used to detectSDB events are disclosed in U.S. Pat. No. 7,882,834 to Gradon et al.,entitled “Autotitrating Method and Apparatus,” issued Feb. 8, 2011, theentire contents of which is hereby incorporated by reference in itsentirety.

If the control system 224 is transitioning from an awake state to asleep state, or if the pressure is transitioning to the pressure range(e.g., whether or not it starts at the awake pressure), the pressure canchange with a rate of change configured to reduce or eliminatediscomfort associated with large pressure changes. The rate of change ofpressure, or the ramp up rate, can be selected, adjusted, or configuredby a user. In some embodiments, the ramp up rate can be a constant or itcan vary based at least in part on data acquired with the sensors orother relevant data. During the transition, the control system 224 canbe configured to ignore SDBs detected in block 415.

When the pressure reaches the pressure range, the control system 224 canemploy control methods which adjust the pressure within the pressurerange based at least in part on any detected SDB events or lack thereof(e.g., normal breathing) in block 420. Various methods of control orcontrol algorithms are possible, including the methods described in PCTPublication Number WO 2012/020314, filed Aug. 12, 2011 and entitled“APPARATUS AND METHOD FOR PROVIDING GASES TO A USER,” which isincorporated by reference herein in its entirety.

If the patient is awake, the method 400 proceeds from block 410 to block425 where the control system 224 controls the PAP system to supplybreathing gases at an awake pressure, the awake pressure lower than orequal to the lower bound of the pressure range. If the control system224 is transitioning from an asleep state to an awake state, or if thepressure is transitioning to the awake pressure (e.g., whether or not itstarts in the pressure range), the pressure can change with a rate ofchange configured to reduce or eliminate discomfort associated withlarge pressure changes. The rate of change of pressure, or the ramp downrate, can be selected, adjusted, or configured by a user. In someembodiments, the ramp down rate can be a constant or it can vary basedat least in part on data acquired with the sensors or other relevantdata.

After completion of the operations in block 420 or block 425, the method400 then returns to block 405 where the control system 224 detects thesleep state of the patient. The control loop can thus proceed in acontinuous loop to control the PAP system and respond to changes in thepatient's sleep state and to sleep disordered breathing events.

CONCLUSION

Examples of PAP systems and methods which provide a range of pressuresfor sleeping patients and a lower pressure for awake patients have beendescribed with reference to the figures. The representations in thefigures have been presented to clearly illustrate principles related toPAP therapy having an awake pressure setting, and details regardingdivisions of modules or systems have been provided for ease ofdescription rather than attempting to delineate separate physicalembodiments. The examples and figures are intended to illustrate and notto limit the scope of the embodiments described herein.

As used herein, the term “controller” or “processor” refers broadly toany suitable device, logical block, module, circuit, or combination ofelements for executing instructions. For example, the controller 305 caninclude any conventional general purpose single- or multi-chipmicroprocessor such as a Pentium® processor, a MIPS® processor, a PowerPC® processor, AMD® processor, ARM® processor, or an ALPHA® processor.In addition, the controller 305 can include any conventional specialpurpose microprocessor such as a digital signal processor. The variousillustrative logical blocks, modules, and circuits described inconnection with the embodiments disclosed herein can be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.The controller 305 can be implemented as a combination of computingdevices, e.g., a combination of a DSP and a microprocessor, a pluralityof microprocessors, one or more microprocessors in conjunction with aDSP core, or any other such configuration.

Data storage 310 can refer to electronic circuitry that allowsinformation, typically computer or digital data, to be stored andretrieved. Data storage 310 can refer to external devices or systems,for example, disk drives or solid state drives. Data storage 310 canalso refer to fast semiconductor storage (chips), for example, RandomAccess Memory (RAM) or various forms of Read Only Memory (ROM), whichare directly connected to the communication bus or the controller 305.Other types of memory include bubble memory and core memory. Datastorage can be physical hardware configured to store information in anon-transitory medium.

Conditional language used herein, such as, among others, “can,” “could,”“might,” “may,” “e.g.,” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orstates. Thus, such conditional language is not generally intended toimply that features, elements and/or states are in any way required forone or more embodiments. As used herein, the terms “comprises,”“comprising,” “includes,” “including,” “has,” “having” or any othervariation thereof, are intended to cover a non-exclusive inclusion. Forexample, a process, method, article, or apparatus that comprises a listof elements is not necessarily limited to only those elements but mayinclude other elements not expressly listed or inherent to such process,method, article, or apparatus. Also, the term “or” is used in itsinclusive sense (and not in its exclusive sense) so that when used, forexample, to connect a list of elements, the term “or” means one, some,or all of the elements in the list. Conjunctive language such as thephrase “at least one of X, Y and Z,” unless specifically statedotherwise, is otherwise understood with the context as used in generalto convey that an item, term, etc. may be either X, Y or Z. Thus, suchconjunctive language is not generally intended to imply that certainembodiments require at least one of X, at least one of Y and at leastone of Z each to be present. Language used herein connotingapproximation, estimation, or inexact values, such as, among others,“around,” “about,” “approximately,” and the like, unless specificallystated otherwise, or otherwise understood within the context as used, isgenerally intended to convey that the values described by the languageare within 10% of the stated value, within 5% of the stated value, orwithin 1% of the stated value.

It should be emphasized that many variations and modifications may bemade to the embodiments described herein, the elements of which are tobe understood as being among other acceptable examples. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and protected by the following claims.Further, nothing in the foregoing disclosure is intended to imply thatany particular component, characteristic or process step is necessary oressential.

1.-19. (canceled)
 20. A positive airway pressure device, the devicecomprising: a flow generator configured to provide gas at a pressure toa patient; a sensor configured to measure breathing of the patient; anda control system configured to: detect sleep disordered breathing of thepatient based at least in part on analysis of data acquired by thesensor; determine a sleep state of the patient based at least in part onthe analysis of data acquired by the sensor; control the flow generatorto provide a pressure within an effective therapeutic pressure range,the effective therapeutic pressure range being between a low pressureand a high pressure in response to the sleep state being determined tobe asleep, the pressure provided based at least in part on whether sleepdisordered breathing is detected; and control the flow generator toprovide an awake pressure different from the low pressure in response tothe sleep state being determined to be awake, wherein the control systememploys a transition function to ramp the pressure up from the awakepressure to the effective therapeutic pressure range and ramp thepressure down from the effective therapeutic pressure range to the awakepressure; and wherein sleep disordered breathing is ignored during rampup from the awake pressure to a minimum asleep pressure.
 21. Thepositive airway pressure device of claim 20, wherein the low pressure isgreater than or equal to about 4 cmH₂O.
 22. The positive airway pressuredevice of claim 20, wherein the high pressure is less than or equal toabout 20 cmH₂O.
 23. The positive airway pressure device of claim 20,wherein the ramping up of the pressure to the effective therapeuticpressure range is based on an occurrence of an exit trigger.
 24. Thepositive airway pressure device of claim 23, wherein the exit triggercomprises one or more sleep disordered breathing events.
 25. Thepositive airway pressure device of claim 23, wherein the exit trigger ismultiple sleep disordered breathing events within one or both of apredetermined time period or a number of breaths.
 26. The positiveairway pressure device of claim 23, wherein the exit trigger is twoapnea events within a moving window of 30 consecutive breaths.
 27. Thepositive airway pressure device of claim 23, wherein the exit trigger istwo hypopnea events with in a moving window of 30 consecutive breaths.28. The positive airway pressure device of claim 23, wherein the exittrigger is an event with a sequence of three consecutive flow limitedbreaths.
 29. The positive airway pressure device of claim 20, wherein aramp up rate from the awake pressure to the effective therapeuticpressure range is configured to reduce or minimize discomfort to thepatient.
 30. The positive airway pressure device of claim 29, whereinthe ramp up rate is about +0.1 cmH₂O/s.
 31. The positive airway pressuredevice of claim 20, wherein the controller is further configured todetect if the patient is awake during a transition from the awakepressure to the effective therapeutic pressure range, and to control theflow generator to provide a pressure that is ramped down to the awakepressure.
 32. The positive airway pressure device of claim 31, wherein aramp down rate from the effective therapeutic pressure range to theawake pressure is the same as a ramp up rate from the awake pressure tothe effective therapeutic pressure range.
 33. The positive airwaypressure device of claim 31, wherein a ramp down rate from the effectivetherapeutic pressure range to the awake pressure is different from theramp up rate from the awake pressure to the effective therapeuticpressure range.
 34. The positive airway pressure device of claim 31,wherein a ramp down rate from the effective therapeutic pressure rangeto the awake pressure is selectable by a user.
 35. The positive airwaypressure device of claim 31, wherein a ramp up rate from the awakepressure to the effective therapeutic pressure range is selectable by auser.
 36. The positive airway pressure device of claim 20, wherein theawake pressure is a therapeutic pressure.
 37. A positive airway pressuresystem comprising: the positive airway pressure device of claim 20; apatient interface configured to provide to the patient the gas at thepressure; and a conduit configured to provide a path for the gas fromthe flow generator to the patient interface.